1. Field of the Invention
The present invention relates generally to internal combustion engines and, more specifically, it relates to a double piston cycle engine (DPCE) that is more efficient then conventional combustion engines.
2. Description of the Related Art
It can be appreciated that internal combustion engines are ubiquitous today and have been in use for over 100 years. Typically, an internal combustion engine includes one or more cylinders. Each cylinder includes a single piston that performs four strokes, commonly referred to as the intake, compression, combustion/power, and exhaust strokes, which together form a complete cycle of conventional pistons.
The main problem with a conventional internal combustion engine is low fuel efficiency. It is estimated that more than one half of the potential fuel thermal energy created by conventional engines dissipates through the engine structure without adding any useful mechanical work. A major reason for this thermal waste is the essential cooling requirements of conventional engines. The cooling system (e.g., radiator) alone dissipates heat at a greater rate and amount than the total heat actually transformed into useful work. Another problem with conventional internal combustion engines is their inability to increase efficiencies while using heat regeneration or recycling methods to provide higher combustion temperatures.
Another reason why conventional engines suffer from efficiency problems is that the high-temperature in the cylinder during the intake and compression strokes makes the piston work harder and, hence, less efficient during these strokes.
Another disadvantage associated with existing internal combustion engines is their inability to further increase combustion temperatures and compression ratios; although theoretically raising chamber temperatures during the power stroke and increasing compression ratios would have improve efficiencies.
Another problem with conventional engines is their incomplete chemical combustion process causing harmful exhaust emissions.
While these devices may be suitable for the particular purpose to which they address, they are not as efficient as the proposed DPCE that utilizes temperature differentiated dual cylinders that divide the conventional four strokes of a piston into two low temperature strokes (intake and compression) and two high temperature strokes (power and exhaust), performed by each of the respective dual pistons.
Although others have previously disclosed dual-piston combustion engine configurations, none provide the substantial efficiency and performance improvements of the present invention. For example, U.S. Pat. No. 1,372,216 to Casaday discloses a dual piston combustion engine in which cylinders and pistons are arranged in respective pairs. The piston of the firing cylinder moves in advance of the piston of the compression cylinder. U.S. Pat. No. 3,880,126 to Thurston et al. discloses a two-stroke cycle split cylinder internal combustion engine. The piston of the induction cylinder moves somewhat less than one-half stroke in advance of the piston of the power cylinder. The induction cylinder compresses a charge, and transfers the charge to the power cylinder where it is mixed with a residual charge of burned products from the previous cycle, and further compressed before igniting. U.S. Pat. Application No. 2003/0015171 A1 to Scuderi discloses a four-stroke cycle internal combustion engine. A power piston within a first cylinder is connected to a crankshaft and performs power and exhaust strokes of the four-stroke cycle. A compression piston within a second cylinder is also connected to the crankshaft and performs the intake and compression strokes of the same four-stroke cycle during the same rotation of the crankshaft. The power piston of the first cylinder moves in advance of the compression piston of the second cylinder. U.S. Pat. No. 6,880,501 to Suh et al. discloses an internal combustion engine that has a pair of cylinders, each cylinder containing a piston connected to a crankshaft. One cylinder is adapted for intake and compression strokes. The other cylinder is adapted for power and exhaust strokes. U.S. Pat. No. 5,546,897 to Brackett discloses a multi-cylinder reciprocating piston internal combustion engine that can perform a two, four, or diesel engine power cycle.
However, these references fail to disclose how to differentiate cylinder temperatures to effectively isolate the firing (power) cylinders from the compression cylinders and from the surrounding environment. The references further fail to disclose how to minimize mutual temperature influence between the cylinders and the surrounding environment. In addition, the references fail to disclose engine improvements that further raise the temperature of the firing cylinder and lower the temperature of the compression cylinder beyond that of conventional combustion engine cylinders to enhance engine efficiency and performance. Specifically, minimizing temperature of the compression cylinder allows for a reduced compression work investment, while increasing temperature in the power cylinder allows for increased heat regeneration. In addition, the separate cylinders disclosed in these references are all connected by a transfer valve or intermediate passageway of some sort that yields a volume of “dead space” between cylinders, permitting gases to accumulate in between cylinders and further degrading the efficiency of the engine. Additionally, none of these prior art references discussed above teach an opposed or “V” cylinder and crankshaft configuration that minimizes dead space between cylinders while isolating the cylinders to maintain an improved temperature differential between the cylinders.
U.S. Pat. No. 5,623,894 to Clarke discloses a dual compression and dual expansion internal combustion engine. An internal housing containing two pistons moves within an external housing forming separate chambers for compression and expansion. However, Clarke contains a single chamber that executes all of the engine strokes preventing isolation and/or improved temperature differentiation of cylinders such as those disclosed in the present invention.
U.S. Pat. No. 3,959,974 to Thomas discloses a combustion engine comprising a combustion cylinder formed in part of material which can withstand high temperatures in a ringless section containing a power piston and connected to a ringed section maintaining a relatively low temperature containing another piston. However, elevated temperatures in the entire Thomas engine reside not only throughout the combustion and exhaust strokes, but also during part of the compression stroke. Further, Thomas fails to disclose a method of isolating the engine cylinders in an opposed or “V” configuration to permit improved temperature differentiation and discloses an engine containing substantial dead space in the air intake port connecting the cylinders.
In these respects, the DPCE according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides a dramatically improved internal combustion engine that is more efficient than conventional internal combustion engines.